This invention relates to thermoplastic molding compositions comprised of thermoplastic copolyesters and styrenic/unsaturated dicarboxylic acid anhydride copolymers. More specifically, it relates to the blending of a copolyester with a styrenic/maleic anhydride copolymer (SMA) resulting in a product with good toughness and good clarity.
Thermoplastic polyesters, for example, polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) are molding compositions from which articles with valuable mechanical properties can be produced. However, they have high deformation tendencies at elevated temperatures, low heat distortion temperatures (HDT), and moderate impact strength and toughness. When modifying agents consisting of polymers or copolymers including, for example, an acrylonitrile-acrylatestyrenic copolymer is added, the resulting product displays better dimensional stability, increased HDT's, good impact strength and toughness.
Yet for applications such as refrigerator crisper pans, business machines, covers for personal-computer (PC) printers and the like, additional toughness is required along with increased clarity.
Accordingly, it is a primary object of the present invention to provide a unique blend of copolyester and a styrenic/unsaturated dicarboxylic acid anhydride copolymer that produces a product exhibiting toughness and clarity.